1. Field of the Invention
The present invention relates to electronic packaging.
2. Related Art
An electronic package can house one or more dies, however, active electronic components on a die generate heat during operation. Such heat needs to be removed from a package to avoid overheating and reduced performance. The need for thermal management becomes greater as the number of dies desired to be housed in a single package increases and the operating load of each die increases. For example, thermal management is a significant concern for high-density packages which include multiple dies in a relatively small area. Further, dies are continually expected to include greater numbers of active electronic components such as transistors, and to operate at ever greater clock rates and input/output (IO) speeds. The need to dissipate heat is even more important in high-density packages with dies carrying out significant processing operations at high clock rates.
Two conventional approaches developed by IBM Corp. and NEC Corp. address the problem of heat dissipation on a package level basis in high-performance computers. The IBM approach uses a thermal conduction module (TCM) to cool a high-density flip chip multi-chip module (MCM). This approach however is limited to back side cooling. Active surfaces of dies which are flip-chip bonded only face a substrate and are not directly cooled. Uneven thermal gradients and hots spots can still occur on active die surfaces. The NEC approach provides liquid cooling modules (LCMs). However, these LCMs only contact the exterior of an entire package. In this case too, cooling the package exterior does not directly cool active surfaces of flip-chip bonded dies in a package. Uneven thermal gradients and hot spots can still arise across the dies. See, e.g., Advanced Electronic Packaging with Emphasis on Multichip Modules, edited by W. Brown, Chapter 13, “Mainframe Packaging: The Thermal Conduction Module,” published by I.E.E.E. Press, Piscataway, N J, 1999, pp. 492-565. More effective cooling of active electronic components within an electronic package is needed.